a. Field of the Invention
This disclosure relates to a rotational coupling device. In particular, the disclosure relates to a rotational coupling device that enables transfer of torque to an output member from either of two input members to drive the output member in different rotational directions and/or at different speeds.
b. Background Art
Rotational coupling devices such as clutches and brakes are used to control transfer of torque between rotational bodies. One conventional application for a rotational coupling device is the transfer of a driving torque to a fan used in cooling a vehicle or another apparatus. For example, puller fans are often used to pull cooler air through a vehicle's radiator to assist in cooling components of the vehicle. By reversing the direction of rotation of the fan, the same fan can also be used to expel heat from the vehicle and/or to expel contaminants (e.g., plant debris) from the vehicle's radiator. Conventional rotational coupling devices used with cooling fans are only capable of transferring rotational torque to drive the fan in one rotational direction. Reversing the direction of the fan therefore requires a separate structure such as a motor. Another conventional application for a rotational coupling device is to transfer a driving torque from a vehicle engine to an alternator or other vehicle accessory. It is desirable, however, to be able to drive the alternator or other accessories at different speeds (e.g., at a higher speed when the vehicle is idling and at a lower speed when the vehicle is in motion) and many conventional rotational coupling devices are only capable of driving the alternator or accessory at one speed.
The inventors herein have recognized a need for a rotational coupling device that will minimize and/or eliminate one or more of the above-identified deficiencies.